1. Field of the Invention
The present invention relates to a rotation mechanism arranged to expose an interior of an automatic document transportation device.
2. Description of the Related Art
Conventionally, an automatic document transportation device having a configuration of including a rotation mechanism arranged to expose an interior is known and an image processing device equipped with this type of automatic document transportation device is also known in the prior art.
The prior art discloses an image processing device configured as below. The conventional image processing device includes a cover unit arranged in a freely rotating manner about a supporting shaft between an operation position of covering an upper surface of a device main body incorporating an image processing unit and a standby position of opening the upper surface. The conventional image processing device also includes a biasing unit for generating a biasing force for rotating the cover unit toward the standby position side to prevent the cover unit from dropping from the standby position toward the operation position due to weight of the cover. The conventional image processing device further includes a stopping unit for causing the cover unit to be in an immovable state at the operation position. The biasing unit and the stopping unit are arranged at a common base fixed to the device main body.
The configuration disclosed in the prior art alleviates an impact when the cover unit drops, since an arc-shaped gear meshes with a torque gear when the cover unit rotates. Such a configuration exhibits a resistance force while the arc-shaped gear meshes with the torque gear, but the resistance is no longer applied at the time that the meshing of the arc-shaped gear and the torque gear is released. Thus, the arc-shaped gear needs to be made as long as possible. If the arc-shaped gear is long, however, the possibility of the arc-shaped gear interfering with another member when the cover unit rotates becomes higher.
The following configuration has been considered for improving the above described problems. This configuration includes a wheel shaped gear portion that integrally rotates with a frame and is arranged on the same axis line as the center of rotation of the frame rotatably supported to open one part of a document transportation path. A resistance unit for applying resistance to the gear portion is arranged to mesh with the gear portion. According to such a configuration, an automatic document transportation device capable of continuously applying the resistance over the entire range of the rotation stroke of the frame can be realized with a simple configuration. This configuration, however, has a drawback in that the gear portion is subjected to a force in the direction of releasing the meshing with the resistance unit by the resistance of the resistance unit at the time of the rotation of the frame and the gear portion rides over the resistance unit (floating of the gear portion). Thus, if such a configuration is adopted, a dedicated member for preventing the floating of the gear portion must be added. However, the addition of a dedicated member leads to an increase in the manufacturing cost and an increase in the number of components. Therefore, improvement can still be made from the standpoint of enhancing the productivity in the configuration of arranging the gear portion that integrally rotates with the frame on the same axis line as the center of rotation of the frame.